The White House and its Western allies said a United Nations report on last month's chemical attack in Syria added powerful evidence to their view that regime forces fired sarin-filled rockets, and redoubled their push for harsh international measures.

U.S. and independent weapons experts, meanwhile, identified surface-to-surface rockets described in the long-awaited U.N. report as Russian—the same kind the U.S. said were used in previous attacks by Syrian President
Bashar al-Assad's
forces.

WSJ national security correspondent Adam Entous analyzes how the U.S. took unexpected turns to get itself engulfed in the Syria crisis as well as how the U.S. was able to back away as well. Photo: AP

U.N. Report of Chemical Weapons Investigation

The attacks outside Damascus on Aug. 21 also relied on rockets that, based on the U.N. descriptions, were of an Iranian design, though they may have been manufactured in Syria, the experts said.

The U.N. investigation wasn't aimed at assigning blame, and Monday's report doesn't directly accuse Mr. Assad. Still, Secretary-General Ban Ki-moon said those guilty should be brought to justice by world powers. "This is a war crime and a violation of international law," he said.

U.S. officials said the new U.N. documentation, showing the use of high-quality sarin gas and military-grade rockets and launchers, reinforced their case that Mr. Assad's forces were responsible.

ENLARGE

French Foreign Affairs minister Laurent Fabius, center, U.S. Secretary of State John Kerry, right, and British Foreign Affairs Secretary William Hague, left, give a press conference after talks on the Syria crisis on Monday in Paris, France.
Agence France-Presse/Getty Images

"The more countries around the world are confronted with the hard fact of what occurred on Aug. 21, the more they recognize that the steep price of impunity for Assad could extend well beyond Syria," said Samantha Power, the U.S. ambassador to the U.N. Ms. Power said the report's "technical details make clear that only the regime could have carried out this large-scale chemical-weapons attack."

Russia's ambassador to the U.N., Vitaly Churkin, said Western officials had jumped to conclusions by saying the report proves government responsibility. "Allegations that it was in fact the opposition that used chemical weapons on Aug. 21 cannot be simply shrugged off," Mr. Churkin said. "Those allegations must be investigated."

The chemical attack provoked a threat of military action from President Barack Obama, who set the threat aside when Russia proposed a process for dismantling Syria's chemical-weapons arsenal.

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The U.S. and its allies on the U.N. Security Council said Monday that they will renew a push for an international resolution to disarm Syria that contains the threat of penalties—if not military force—for a failure by Damascus to comply.

Secretary of State
John Kerry
agreed in talks with Russia that the resolution wouldn't threaten military force. But U.S. and Western officials said Monday they wanted to ensure the resolution was as strict as possible.

A key dispute is whether the resolution should come under Chapter 7 of the U.N. Charter, which in some instances permits the use of military action for enforcement.

"The Syrian regime has no choice but to commit to eliminating these chemical weapons," said French Foreign Minister
Laurent Fabius,
who met Monday with Mr. Kerry in Paris. "All of the options remain on the table."

The disarmament deal, struck in talks between U.S. and Russian officials over the weekend, will be tested this week, when Syria faces a Friday deadline for a full disclosure of its arsenal to The Hague-based Organization for the Prohibition of Chemical Weapons, which administers a global ban on such arms and will help dismantle Syria's program.

U.N. inspectors spent several days outside Damascus gathering evidence for their report on last month's attack, gathering blood samples, rocket fragments and other evidence. Mr. Ban said 85% of the blood samples tested positive for sarin, as did the majority of rocket fragments.

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The investigators examined rocket fragments in detail, and the report shows some with markings in Cyrillic lettering.

Mr. Churkin said he didn't know what the significance of the Cyrillic markings were. "We need to have experts look into it," he said.

However the markings led some Western officials to conclude the arms originated in Russia, which is Syria's largest arms supplier. "Just look at them," said one U.S. official. "There is Cyrillic on the munitions."

The group Human Rights Watch, in an earlier investigation into last month's attack, concluded that the markings indicated the munition was a Soviet-era M-14 rocket.

The U.N.'s findings correspond to conclusions reached by Human Rights Watch, which issued its own report last week based on an investigation of video and photographic evidence.

"The U.N. report is adding more evidence to support the conclusion of our own investigation, which was pointing to government responsibility for the chemical attack," said Philippe Bolopion, U.N. director for Human Rights Watch.

The report identifies a second, larger rocket that a former Pentagon intelligence analyst said was based on an Iranian blueprint, but possibly made in Syria.

The launchers used to shoot those rockets are held only by the Syrian military, the former intelligence analyst said.

Mark Lyall Grant, the British ambassador, added that the trajectories of the rockets and types of munitions leave "no doubt that it was the regime that used chemical weapons."

The report says an East/Southeast trajectory could be determined on two of the five impact sites studied. The report doesn't name the geographic location of where the sarin-filled rockets were fired from.

Mr. Grant said Ake Sellstrom, the head of the U.N. inspectors, told a closed-door United Nations Security Council meeting on Monday that the sarin used was "35 times the amount" used in the 1995 Tokyo subway attack and was higher quality than that used by Iraq in the Iran-Iraq war.

The report itself makes no mention of the sarin's quality. Nor does it say how many people died. The U.S. has said more than 1,400 were killed.

In a related action Monday, Mr. Obama signed an order to allow the U.S. to help protect Syrians against chemical-weapons attacks, including protective gear and training.

White House press secretary Jay Carney said Monday's U.N. report supports the conclusion already reached by the U.S.—that the Assad regime is responsible for the Aug. 21 attack.

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